Wednesday, December 22, 2010

The compound which gives chillies their kick is being used in the fight against chronic pain.

Researchers at Aberdeen University have identified how genes are "turned on" to make humans feel pain.

Capsaicin, the compound in chillies which gives them their kick, can also turn on the switch.

It is believed the study could herald the development of new painkilling drugs.

The team looked at the mechanics of the pain gene known as substance-P which was first associated with chronic inflammatory pain more than 30 years ago.

Genes need "switches", known as promoters and enhancers, to turn them on in the right place, at the right time and at the right level.

One of the major findings of the study was that the switches do not act in isolation and need other switches to "speak to" in order to activate the gene.

Researchers based in the university's Kosterlitz Centre for Therapeutics spent five years looking for the switches that turn the substance-P gene on in a group of cells called sensory neurones.

Dr Lynne Shanley said: "Finding the switch was like looking for a needle in a haystack.

"However, by comparing the genetic sequences of humans, mice and chickens, we were able to find a short stretch of DNA that had remained unchanged since before the age of dinosaurs.

"We were delighted when this little bit of DNA turned out to be a genetic switch, or enhancer sequence, which could turn on the substance-P gene in sensory neurones."

Marissa Lear, head technician on the project, said: "Because the switch was active in these sensory neurones we applied capsaicin, the 'hot' chemical in curry and chilli, to see if the switch could be turned on and, amazingly, it was."

Chronic inflammatory pain in the form of arthritis and other conditions affects thousands of people in the UK each year and in many cases is untreatable.

Capsaicin has previously been used as treatment for chronic pain.

The scientists said understanding the genetic mechanisms that allow capsaicin to induce inflammatory pain will lead to a better understanding of the pain process.

Professor Ruth Ross, head of the Kosterlitz centre and a co-author of the paper, said: "Understanding the genetic processes that trigger inflammatory pain is essential to developing new therapies.

"Finding this new substance-P enhancer sequence, and showing that it can respond to capsaicin, has allowed us to add another part of the complex jigsaw puzzle that makes up the inflammatory pain response."